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iFeC Appendix E,Worksheet E-1 <br /> Residential Combustion Air Calculation Method <br /> (for Furnace,Boller,and/or Water Heater in the Same Space) <br /> Step 1:Complete vented combustion appliance Information. <br /> Fur ace/Boller: <br /> Draft Hood Fan Assisted Direct Vent Input: <br /> (Not fan assisted) &Power Vent (BzZQM Btu/hr <br /> Water Heater: <br /> Draft Hood Fan Assisted Direct Vent Input: <br /> (Not fan assisted) &Power Vent -19,20D Btu/hr <br /> Step 2:Calculate the volume of the Combustion Appliance Space(CAS)containing combustion appliances, <br /> The CAS includes all spaces connected to one another <br /> by code compliant openings. CAS volume:Z.250fb <br /> Step 3:Determine Air Changes per Hours(ACH)x <br /> Default ACH values have been incorporated Into Table E-1 for use with Method 4b(KAIR Method).If the <br /> year of construction or ACH is not know,use method 4a(Standard Method). <br /> Step 4:Determine Required Volume for Combustion Air.. <br /> 4a.Standard Method <br /> Total Btu/hr input of all combustion appliances Input;-ZSf Btu/hr <br /> (DO NOT COUNT DIRECT VENT APPLIANCES) <br /> Use Standard Method column in Table E-1 to find Total Required Volume(TRV) TRV: 5v'L 5, f#a <br /> IF CAS Volume(from Step 2)is greater than TRV then no outdoor openings are needed. <br /> If CAS Volume(from Step 2)Is less than TRV then go to STEP S. <br /> 4b.Known Air Infiltration Rate(KAIR)Method <br /> Total Btu/hr input of all fan-assisted and power vent appliances <br /> (DO NOT COUNT DIRECT VE NT APPLIANCES) Input:----.,—Btu/hr <br /> Use Fan-Assisted Appliances column In Table E-1 to find <br /> Required Volume Fan Assisted(RVFA) RVFA: _ _ fts <br /> Total Btu/hr input of all non-fan-assisted appliances Input: Btu/hr <br /> Use Non-Fan-Assisted Appliances column In Table E-1 to find <br /> Required Volume Non-Fan-Assisted(RVNFA) RVNFA: fts <br /> Total Required Volume(TRV)=RVFA+RVNFA RV= + - fts <br /> If CAS Volume(from Step 2)is greater than TRV then no outdoor openings are needed. <br /> If CAS Volume(from Step 2)is less than TRV then go to STEP S. <br /> Step 5:Calculate the ratio of available interior volume to the total required volume, �(- <br /> Ratio=CAS Volume(from Step 2)divided by TRV(from Step 4a or Step 4b) Ratio <br /> Step 6:Calculate Reduction Factor(RF). <br /> RF-1 minus Ratio RF=1- <br /> Step 7:Calculate single outdoor opening as if all combustion air is from outside. <br /> Total Btu/hr Input of all Combustion Appliances in the same CAS(EXCEPT DIRECT VENT) Input: OX Btu/hr <br /> Combustion Air Opening Area(CAOA): <br /> Total Btu/hr divided by 3000 Btu/hr per int CAOA= C1C�'3000 Btu/hr per ln2= 2`7 int <br /> Step 8:Calculate Minimum CAOA. <br /> r <br /> Minimum CAOA=CAOA multiplied by RF Minimum CAOA= 2 x r ' 1`7 In2 <br /> Step 9:Calculate Combustion Air Opening Diameter(CAOD) <br /> CAOD=1.13 multiplied by the square root of Minimum CAOA CAOD=1.13 Minimum CAOA <br /> 1 If desired,ACH can be determined using ASHME calculation or blower door test.Follow procedures in Section G304. <br /> i <br />